1. Field of the Invention
This invention relates to an optical fiber switching device and method for selectively switching coupling between a plurality of first optical fibers and a plurality of second optical fibers which are respectively coupled with each other.
2. Related Background of Art
Recently there are found increasing developments in the field of optical communication. Taking into consideration the present circumstances that optical communication is introduced in main lines, it is urgently needed to make up large-scale wiring networks for coupling a number of optical fibers in matrix arrangements which are different from the conventional point-to-point relay transmission system.
A conventional optical fiber switching device comprises, although not illustrated here, a plurality of guide rails which are arranged perpendicular to each other, and slide terminals slidably mounted on the guide rails, and optical fibers respectively secured to the respective slide terminals, whereby the slide terminals are slid to couple required ones of the optical fibers (see "1.times.1000 Optical Switch for 10-Fiber Ribbon" Spring General Conference of The Institute of Electronics, Information and Communication Engineers (1989), ps. 4-238)
In this optical fiber switching device, surplus portions of optical fibers fed to the slide terminals are adjusted by an optical fiber length adjusting mechanism located outside.
On the other hand, another conventional optical fiber switching device comprises, although not illustrated, a number of first optical fibers arranged in a matrix on one side of a coupling board, and a number of second optical fibers arranged in matrix on another side of the coupling board, the first and the second optical fibers being coupled with each other.
In switching a selected one of the second optical fibers, inconveniently an operator selects a required one out of the second optical fibers, pull out the selected second optical fiber out of the coupling board, and couples the selected second optical fiber with a required one of the first optical fibers.
The conventional optical fiber switching devices having the above-described structure have the following disadvantages.
Firstly, when a plurality of optical fibers have to be coupled, the optical fibers congest the sides of the coupling board, with results that the coupling operational efficiency is lowered, and erroneous coupling frequently takes place.
Especially in switching one slide terminal to a required slide terminal, the congestion of a plurality of optical fibers is unavoidably a serious problem.
Secondly, the problem of the above-described congestion can be solved by securing a large space sufficient for the coupling, but unpreferably securing a large space makesa size of the devices large.
Thirdly, in accordance with an increase of a number of the slide terminals accompanied by that of a number coupling of optical fibers, the guide rails have to be extended, which is a problem from the viewpoint of the rigidity of the devices.
Fourthly, without the guide rails, it will become very difficult to maintain a connecting force of the connectors, and the congestion of neighboring optical fibers causes s problems.
Fifthly, since a master optical fiber connected to a slide terminal is coupled to one of a number of optical fibers arranged on a connector table in a matrix, the devices are not adaptable to large-capacity optical communication on the side of subscribers.
Sixthly, since an operator selects an arbitrary one of the second optical fibers and switches its connection, the maintenance is so inefficient that high running costs cannot be avoiced.
Finally, there is a considerable high possibility that when an operator selects and switch a required second optical fiber, the other optical fibers which have not been selected are damaged.
An object of this invention is to provide an optical fiber switching device which can solve the above-described problems.